Devices for centering spectacle lenses

ABSTRACT

This invention is concerned with devices for centering spectacle lenses, in which the lens is located on a support or mount by means of a rubber cap or the like, so that by copying a template or pattern in a grinding machine the lens is given its desired peripheral shape, the de-centering of the lens vis-a-vis the central rotation point of the template or the mount is transmitted onto a reference plate with a graded scale at the edge and a center cross or other index mark.

Ulllle Dulles iallelll Reiner et al.

DEVICES FOR CENTERING SPECTACLE LENSES Inventors: Josef Rudolf Reiner,Rodenkirchen; Gunther Paul Theodore Schramm, shet aftlqxn ayt Assignee:Firma Wernicke & Co., K.G., Dusseldorf-Eller, Germany Filed: Nov. 19,1971 Appl. No.: 200,542

Foreign Application Priority Data Nov. 28, 1970 Germany ..P 20 58 651.0

U.S. Cl. ..356/l72, 356/153, 356/168,

356/169, 356/171 Int. Cl. ..G0lb 11/26 Field of Search ..356/l72, 168,169,

[451 June 5,1973

[56] References Cited UNITED STATES PATENTS 3,586,448 6/1971 Beasse..356/l72 3,684,384 8/1972 Hojo et al. ..356/l68 X 2,675,738 4/1954Ellis et al ..356/l53 Primary Examiner-Ronald L. Wibert AssistantExaminer -Paul K. Godwin Attorney-James M. l-leilman [57] ABSTRACT Thisinvention is concerned with devices for centering spectacle lenses, inwhich the lens is located on a support or mount by means of a rubber capor the like, so that by copying a template or pattern in a grindingmachine the lens is given its desired peripheral shape, the de-centeringof the lens vis-a-vis the central rotation point of the template or themount is transmitted onto a reference plate with a graded scale at theedge and a center cross or other index mark.

5 Claims, 2 Drawing Figures DEVICES FOR CENTERING SPECTACLE LENSES Thisinvention is concerned with devices for centering spectacle lenses, inwhich the lens is located onasupport or mount by means of a rubber capor the like, so that by copying a template or pattern in a grindingmachine the lens is given its desired peripheral shape, the de-centeringof the lens via-a-vis the central rotation point of the template or themount is transmitted onto a reference plate with a graded scale at theedge and a center cross or other index mark.

It is usual to mark the center rotation point of the lens, but errorsoften occur during this marking in particular with cylindrical lensesand therefore, it has been suggested to locate a partially reflectingsurface between the eye of the person using the device and the spectaclelens, by means of which surface a reference plate, carrying a scale anda central cross is imaged into the observation ray path. This makes itpossible, by means of simultaneous observation of the spectacle lens andthe image of the scale and of the de-centering of the central cross ofthe plate, to fix the spectacle lens while bearing in mind thedecentering of its optical centre, and the position of the cylinder axisin cylindrical lenses, on the rubber cap or the like without anymarking. The template is arranged behind the plate and is used for theworking of the edge of the spectacle lens. The observer can see whetherin the case of multifocal lenses the near portion is of sufficient sizeand is in the correct position in the lens. However it is not possibleto observe the spectacle lens, the reference plate and also the templatesimultaneously.

An aim of the invention is to make simultaneous observation of thespectacle lens and the reference plate without any parallax.

According to the invention the reference plate is made adjustabletowards and away from the partially reflecting mirror.

It was recognized that parallax errors frequently occur when thespectacle lens is sharply curved or when the lens shows pronouncedvariation in thickness from a previously mounted lens; the distancebetween the spectacle lens surface on which sights have been taken andthe mirror changes relative to the distances of the mirror from theplate. If in accordance with the invention, the plate is adjustabletowards and away from the mirror it is possible with simple means tokeep the relation between the distances from the plate to the mirror andfrom the latter to the spectacle lens constant, by which means parallaxis eliminated.

A template carrier located behind the plate may also be adjustabletowards and away from the mirror so that the template and carrier areadjustable together. In this case it is sufficient to adjust .the platejointly with the template in such a way that the dividing plane betweenthe plate and the template lies at a distance from the mirror whichcorresponds to the distance of the mirror from the spectacle lens.

Fairly small corrections are therefore possible by means of a simpleadjustment means, e.g. a screw. Preferably the template carrier isadjustable towards and away from the mirror, and the plate is adjustablerelative to the carrier in the plane of the plate in two directionsperpendicular to each other and is rotatable around its center point,and is so connected to the template carrier that the plate can movetowards and away from the mirror with the carrier.

The spectacle lens is preferably adjustable by means of its mount or asupport for the latter, towards and away from the mirror.

Two embodiments of the invention are represented in the accompanyingdrawings in which:

FIG. 1 shows a device in which the reference plate and the templatecarrier are adjustable separately from each other; and

FIG. 2 shows a device in which the plate is adjustable together with thetemplate carrier towards and away from the mirror.

A mount secured to a support 3 l to which a spectacle lens 5 is to beattached is detachably secured concentric with the optical axis 2 of thecentering device by means of a part of the latter. The mount is providedwith a rubber cap 4, by means of which the lens can be fixed to themount in a desired position by reference to the superimposed image of areference plate 9, which is provided with an edge scale and a centercross 13.

The spectacle lens 5 has an axial marking 51, and markings 52 whichdesignate the cylinder axis can also be provided on the lens. Themarkings on the spectacle lens and also a center marking 41 of the mount1 can be observed through an aperture 6 on the axis 2, a magnifying lens7 being placed in front of the observers eye To superimpose a a virtualimage of the plate 9 on the view of the lens 5, a tilted mirror 10 isplaced between aperture 6 and the .spectacle lens 5, the center point Mof the mirror being at a distance a from the center plane of thespectacle lens 5. The mirror partly reflects and partly transmits lightfalling on it. The reference plate 9 can be adjusted, with the help of ascrew 95, in the direction of the arrow K. The Plate 9 can further beadjusted perpendicular to the plane of the drawing by means of similaror identical means, which are not shown, and may be rotatable around itscentral axis. The center plane of the plate 9 is at a distance b fromthe center point M of the mirror 10.

The plate 9 is also mounted to move in the direction of the arrows Stowards and away from the mirror 10 and can thereby be set so that thedistance a is equal to the distance b and all parallax is thereforeeliminated, when the observing eye 8 is aware of both the spectacle lens5 and the plate 9.

A template carrier 12 is located underneath the plate 9 and on thisrests a template 11 which can be seen via the mirror 11 while thespectacle lens 5 and the plate 9 are being observed, and by this meansit is possible for the observer to see whether the spectacle lens is ofthe required size after the desired de-centering, and whether the nearpart of a bifocal lens is in the correct position and has the correctsize. The carrier 12 is preferably also adjustable with the template 11in the direction of the double arrow T towards and away from the mirror10.

A source of light in the form of an incandescent lamp 102 can beprovided, between which and the mirror 10 is located a ground-glassplate 101.

Inthe embodiment shown in FIG. 2 the spectacle lens 5, the mirror 10,and the aperture 6 and the magnifying lens 7 are located in the samemanner as in the embodiment according to FIG. 1. The incadescent lamp102 and the ground-glass plate lfll'also have the same position. Theplate 9 is however laid directly on the template 11 and the carrier 12can be adjusted together with the plate 9 in the direction of the doublearrow R,

towards the mirror and away from the latter. The parts of the device areso arranged that the template can be easily removed from its shownposition between the carrier 12 and the plate 9 or a new template can beput in its place.

If it is required to observe the plate 9 free from the effects ofparallax, then care is taken that the center plane of the plate 9, inthe embodiment according to FIG. 1, has the same distance b from themirror center point M as the point M has from the center plane of thespectacle lens 5 (distance a). Parallax-free adjustment of the plate 9is generally sufficient, as it is then possible to obtain an adequatelysharp image of the template 11 which is sufficient for determining thesize of the lens Distances a, b, and c are indicated by well known scalemeans (not shown)..

It is also possible, however, to choose an adjustment in which, as shownin FIG. 2, the dividing plane between the parts 9 and 11 has a distancefrom the point M which corresponds to the distance between this pointand the lens 5.

The distance c of the carrier in FIG. 1 corresponds approximately to thedistance b in the same figure.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. Apparatus for centering untrimmed spectacle lenses in relationship toa template in preparation for grinding the lens periphery to match thetemplate size and shape comprising; optical means for observation of anuntrimmed spectacle lens mounted on an adjustable support, said meansincluding an eye lens; a partially reflecting mirror mounted between thespectacle lens and the eye lens, set at an angle for reflecting lightfron another direction into the eye lens; a template having a desiredshape and size to insure subsequent mounting in a mounting frame, saidtemplate mounted adjacent to said mirror so that light from the templateis reflected from the mirror into the eye lens, thereby forming avirtual image superposed on that of the spectacle lens; and adjustingmeans for moving the template toward or away from the mirror toeliminate parallax.

2. Apparatus according to claim 1 wherein a transparent reference plateis mounted adjacent to the template substantially parallel thereto andbetween the template and said mirror, said reference plate formed with asymbol designating its center.

3. Apparatus according to claim 2 wherein the reference plate isadjustable in its own plane to move the virtual image of its centersymbol relative to the center of the spectacle lens.

4. Apparatus according to claim 1 wherein said partially reflectingmirror is positioned at an angle of 45 with the line of sight betweenthe center of the eye lens and the center of the spectacle lens.

5. Apparatus according to claim 1 wherein a source of illumination ispositioned above the partially reflecting mirror for illuminating boththe spectacle lens and the template.

1. Apparatus for centering untrimmed spectacle lenses in relationship toa template in preparation for grinding the lens periphery to match thetemplate size and shape comprising; optical means for observation of anuntrimmed spectacle lens mounted on an adjustable support, said meansincluding an eye lens; a partially reflecting mirror mounted between thespectacle lens and the eye lens, set at an angle for reflecting lightfron another direction into the eye lens; a template having a desiredshape and size to insure subsequent mounting in a mounting frame, saidtemplate mounted adjacent to said mirror so that light from the templateis reflected from the mirror into the eye lens, thereby forming avirtual image superposed on that of the spectacle lens; and adjustingmeans for moving the template toward or away from the mirror toeliminate parallax.
 2. Apparatus according to claim 1 wherein atransparent reference plate is mounted adjacent to the templatesubstantially parallel thereto and between the template and said mirror,said reference plate formed with a symbol designating its center. 3.Apparatus according to claim 2 wherein the reference plate is adjustablein its own plane to move the virtual image of its center symbol relativeto the center of the spectacle lens.
 4. Apparatus according to claim 1wherein said partially reflecting mirror is positioned at an angle of45* with the line of sight between the center of the eye lens and thecenter of the spectacle lens.
 5. Apparatus according to claim 1 whereina source of illumination is positioned above the partially reflectingmirror for illuminating both the spectacle lens and the template.